Non-freezing storage unit

ABSTRACT

The present invention discloses a non-freezing storage unit including an outer casing with an open front surface, a drawer which can be pulled out through the open front surface of the outer casing, a sensor installed on the outer casing and/or the drawer, a heater installed in the outer casing, and an air layer formed at the front of the drawer to intercept the cool air. The non-freezing storage unit is located in a cooling space to store food in a non-frozen state at a temperature below 0° C.

TECHNICAL FIELD

The present invention relates to a non-freezing storage unit, and, moreparticularly to, a non-freezing storage unit which can store foodrequiring high-level freshness, such as meat and vegetables, at atemperature below 0° C. without freezing the food.

BACKGROUND ART

Supercooling means the phenomenon that a molten object or a solid is notchanged although it is cooled to a temperature below the phasetransition temperature in an equilibrium state. A material has a stablestate at every temperature. If the temperature is slowly changed, theconstituent elements of the material can follow the temperature changes,maintaining the stable state at each temperature. However, if thetemperature is suddenly changed, since the constituent elements cannotbe changed to the stable state at each temperature, the constituentelements maintain a stable state of the initial temperature, or some ofthe constituent elements fail to be changed to a state of the finaltemperature.

For example, when water is slowly cooled, it is not temporarily frozenat a temperature below 0° C. However, when water enters a supercooledstate, it has a kind of quasi-stable state. As this unstable equilibriumstate is easily broken even by slight stimulation, water tends to moveto a more stable state. That is, if a small piece of material is putinto the supercooled liquid, or if the liquid is suddenly shaken, theliquid starts to be frozen at once such that its temperature reaches thefreezing point, and maintains a stable equilibrium state at thistemperature.

In general, an electrostatic atmosphere is made in a refrigerator andmeat and fish are thawed in the refrigerator at a minus temperature. Inaddition to the meat and fish, fruit is kept fresh in the refrigerator.

This technology uses a supercooling phenomenon. The supercoolingphenomenon indicates the phenomenon that a molten object or a solid isnot changed although it is cooled to a temperature below the phasetransition temperature in an equilibrium state.

This technology includes Korean Patent Publication No. 2000-0011081titled “Electrostatic field processing method, electrostatic fieldprocessing apparatus, and electrodes therefor”.

FIG. 1 is a view of an example of a conventional thawing andfreshness-keeping apparatus. A keeping-cool room 1 is composed of athermal insulation material 2 and an outer wall 5. A mechanism (notshown) controlling a temperature inside the room 1 is installed therein.A metal shelf 7 installed in the room 1 has a two-layer structure.Target objects to be thawed or freshness-kept and ripened such asvegetables, meat and marine products are loaded on the respectivelayers. The metal shelf 7 is insulated from the bottom of the room 1 byan insulator 9. In addition, since a high voltage generator 3 cangenerate 0 to 5000 V of DC and AC voltages, an insulation plate 2 a suchas vinyl chloride, etc. is covered on the inside of the thermalinsulation material 2. A high-voltage cable 4 outputting the voltage ofthe high voltage generator 3 is connected to the metal shelf 7 afterpassing through the outer wall 5 and the thermal insulation material 2.When a user opens a door installed at the front of the keeping-cool room1, a safety switch 13 (see FIG. 2) is turned off to intercept the outputof the high voltage generator 3.

FIG. 2 is a circuit view of the circuit configuration of the highvoltage generator 3. 100 V of AC is supplied to a primary side of avoltage regulation transformer 15. Reference numeral 11 represents apower lamp and 19 a working state lamp. When the door 6 is closed andthe safety switch 13 is on, a relay 14 is operated. This state isdisplayed by a relay operation lamp 12. Relay contact points 14 a, 14 band 14 c are closed by the operation of the relay 14, and 100 V of AC isapplied to the primary side of the voltage regulation transformer 15.

The applied voltage is regulated by a regulation knob 15 a on asecondary side of the voltage regulation transformer 15, and theregulated voltage value is displayed on a voltmeter. The regulation knob15 a is connected to a primary side of a boosting transformer 17 on thesecondary side of the voltage regulation transformer 15. The boostingtransformer 17 boosts the voltage at a ratio of 1:50. For example, when60 V of voltage is applied, it is boosted to 3000 V.

One end 0 ₁ of the output of the secondary side of the boostingtransformer 17 is connected to the metal shelf 7 insulated from thekeeping-cool room 1 through the high-voltage cable 4, and the other end0 ₂ of the output is grounded. Moreover, since the outer wall 5 isgrounded, if the user touches the outer wall 5 of the keeping-cool room1, he/she does not get an electric shock. Further, in FIG. 1, when themetal shelf 7 is exposed in the room 1, it should be maintained in aninsulated state in the room 1. Thus, the metal shelf 7 needs to beseparated from the wall of the room 1 (the air performs an insulationfunction). Furthermore, if a target object 8 is protruded from the metalshelf 7 and brought into contact with the wall of the room 1, thecurrent flows to the ground through the wall of the room 1. Therefore,the insulation plate 2 a is attached to the inner wall to prevent dropof the applied voltage. Still furthermore, when the metal shelf 7 iscovered with vinyl chloride without being exposed in the room 1, anelectric field atmosphere is produced in the entire room 1.

In the prior art, an electric field or a magnetic field is applied tothe received object to be cooled, such that the received object enters asupercooled state. Accordingly, a complicated apparatus for producingthe electric field or the magnetic field should be provided to keep thereceived object in the supercooled state, and the power consumption isincreased during the production of the electric field or the magneticfield.

Additionally, the apparatus for producing the electric field or themagnetic field should further include a safety device (e.g., an electricor magnetic field shielding structure, an interception device, etc.) forprotecting the user from high power, when producing or intercepting theelectric field or the magnetic field.

DISCLOSURE Technical Problem

An object of the present invention is to provide a non-freezing storageunit in which a drawer can be completely pulled out of an outer casing.

Another object of the present invention is to provide a non-freezingstorage unit which can maintain a received object in a supercooled stateonly by the power supply in a space where only the cooling is performed.

A further object of the present invention is to provide a non-freezingstorage unit which includes a handle to compensate for relatively weakthermal insulation in its front surface portion.

Technical Solution

According to an aspect of the present invention, there is provided anon-freezing storage unit, including: an outer casing with an open frontsurface; a drawer which can be pulled out through the open front surfaceof the outer casing; a sensor installed on the outer casing and/or thedrawer; a heater installed in the outer casing; and an air layer formedat the front of the drawer to intercept the cool air, wherein thenon-freezing storage unit is located in a cooling space to store food ina non-frozen state at a temperature below 0° C.

In addition, the air layer is separated from a food storage space in thedrawer by a protruding portion protruding from the front surface of thedrawer.

Moreover, the protruding portion is formed in the shape of ‘┐’ to bebent from the top to bottom.

Further, the air layer is separated from the food storage space in thedrawer by a protruding portion protruding from the bottom surface of thedrawer.

Furthermore, the drawer is provided with a sign to prevent the food frombeing put in a space for defining the air layer.

Still furthermore, a thermal insulation material is filled in the insideof the outer casing.

Still furthermore, when the drawer is completely inserted into the outercasing, the bottom surface, the side surfaces and the rear surface ofthe drawer have a given interval from the outer casing.

Still furthermore, the drawer includes a bulkhead separating the airlayer from the food storage space in the drawer.

Still furthermore, the bulkhead includes an opening portion forcirculating the air in the air layer and the storage room.

Still furthermore, the air layer is separated from the food storagespace in the drawer by a plurality of pins protruding from the bottomsurface of the drawer.

Still furthermore, an opening portion is provided at the front of thebottom surface of the drawer, where the air layer has been formed, suchthat the air can be introduced from the lower portion of the drawer tothe air layer.

Still furthermore, a rib is formed around the opening portion in thebottom surface of the drawer.

Advantageous Effects

According to the non-freezing storage unit provided by the presentinvention, the drawer can be completely pulled out of the outer casing,which improves convenience in use.

In addition, according to the non-freezing storage unit provided by thepresent invention, the air layer is formed at the front portion toinsulate the front portion from the other parts of a refrigerator. Thiscan compensate for a relatively weak thermal insulation effect in thefront portion.

DESCRIPTION OF DRAWINGS

FIG. 1 is a view of an example of a conventional thawing andfreshness-keeping apparatus.

FIG. 2 is a circuit view of the circuit configuration of a high voltagegenerator.

FIG. 3 is a view showing a process in which ice crystal nucleuses areformed in a liquid during the cooling.

FIG. 4 is a view showing a process of preventing the ice crystal nucleusformation, which is applied to an apparatus for supercooling accordingto the present invention.

FIG. 5 is a schematic configuration view of the apparatus forsupercooling according to the present invention.

FIG. 6 is a graph showing a supercooled state of water in the apparatusfor supercooling of FIG. 5.

FIG. 7 is an exploded perspective view of a non-freezing storage unitaccording to an embodiment of the present invention.

FIG. 8 is a perspective view of the non-freezing storage unit accordingto the embodiment of the present invention.

FIG. 9 is a sectional view of the non-freezing storage unit according tothe embodiment of the present invention.

FIG. 10 is a view of a metal plate installed in a drawer of thenon-freezing storage unit according to the embodiment of the presentinvention.

FIG. 11 is a view showing a state where the metal plate is installed inthe drawer of the non-freezing storage unit according to the embodimentof the present invention.

FIG. 12 is a view showing a process in which the drawer of thenon-freezing storage unit of the present invention is inserted into anouter casing.

FIG. 13 is a view showing a state where a contact point portion and asensor installation portion of the non-freezing storage unit of thepresent invention are in contact with each other.

FIG. 14 is an exploded perspective view of a front portion of the drawerincluded in the non-freezing storage unit according to the embodiment ofthe present invention.

FIG. 15 is a view of a first example of an air layer structure includedin the non-freezing storage unit according to the embodiment of thepresent invention.

FIG. 16 is a view of a second example of the air layer structureincluded in the non-freezing storage unit according to the embodiment ofthe present invention.

FIG. 17 is an exploded perspective view of a side casing provided in thenon-freezing storage unit according to the embodiment of the presentinvention.

FIG. 18 is a view of an example in which the non-freezing storage unitaccording to the embodiment of the present invention is applied to aconventional refrigerator.

FIG. 19 is a side-sectional view of the example in which thenon-freezing storage unit of the present invention is applied to theconventional refrigerator.

MODE FOR INVENTION

Hereinafter, the present invention will be described in detail withreference to the exemplary embodiments and the accompanying drawings.

FIG. 3 is a view showing a process in which ice crystal nucleuses areformed in a liquid during the cooling. As illustrated in FIG. 3, acontainer C containing a liquid L (or a received object) is cooled in astoring unit S with a cooling space therein.

For example, it is assumed that a cooling temperature of the coolingspace is lowered from a normal temperature to a temperature below 0° C.(the phase transition temperature of water) or a temperature below thephase transition temperature of the liquid L. While the cooling iscarried out, it is intended to maintain a supercooled state of the wateror the liquid L (or the received object) at a temperature below themaximum ice crystal formation zone (−1° C. to −7° C.) of the water inwhich the formation of ice crystals is maximized, or at a coolingtemperature below the maximum ice crystal formation zone of the liquidL.

The liquid L is evaporated during the cooling such that vapor W1 isintroduced into a gas Lg (or a space) in the container C. In a casewhere the container C is closed, the gas Lg may be supersaturated due tothe evaporated vapor W1.

When the cooling temperature reaches or exceeds a temperature of themaximum ice crystal formation zone of the liquid L, the vapor W1 formsice crystal nucleuses F1 in the gas Lg or ice crystal nucleuses F2 on aninner wall of the container C. Alternatively, the condensation occurs ina contact portion of the surface Ls of the liquid L and the inner wallof the container C (almost the same as the cooling temperature of thecooling space) such that the condensed liquid L may form ice crystalnucleuses F3 which are ice crystals.

For example, when the ice crystal nucleuses F1 in the gas Lg are loweredand infiltrated into the liquid L through the surface Ls of the liquidL, the liquid L is released from the supercooled state and caused to befrozen. That is, the supercooling of the liquid L is released.

Alternatively, as the ice crystal nucleuses F3 are brought into contactwith the surface Ls of the liquid L, the liquid L is released from thesupercooled state and caused to be frozen.

As described above, according to the process of forming the ice crystalnucleuses F1 to F3, when the liquid L is stored at a temperature belowits maximum ice crystal formation zone, the liquid L is released fromthe supercooled state due to the freezing of the vapor evaporated fromthe liquid L and existing on the surface Ls of the liquid L and thefreezing of the vapor on the inner wall of the container C adjacent tothe surface Ls of the liquid L.

FIG. 4 is a view showing a process of preventing the ice crystal nucleusformation, which is applied to an apparatus for supercooling accordingto the present invention.

In FIG. 4, to prevent the freezing of the vapor W1 in the gas Lg, i.e.,to continuously maintain the vapor W1 state, the energy is applied to atleast the gas Lg or the surface Ls of the liquid L so that thetemperature of the gas Lg or the surface Ls of the liquid L can behigher than a temperature of the maximum ice crystal formation zone ofthe liquid L, more preferably, the phase transition temperature of theliquid L. In addition, to prevent the freezing although the surface Lsof the liquid L is brought into contact with the inner wall of thecontainer C, the temperature of the surface Ls of the liquid L ismaintained higher than a temperature of the maximum ice crystalformation zone of the liquid L, more preferably, the phase transitiontemperature of the liquid L.

Accordingly, the liquid L in the container C maintains the supercooledstate at a temperature below its phase transition temperature or atemperature below its maximum ice crystal formation zone.

Moreover, when the cooling temperature in the storing unit S is aconsiderably low temperature, e.g., −20° C., although the energy isapplied to an upper portion of the container C, the liquid L which isthe received object may not be able to maintain the supercooled state.There is a need that the energy should be applied to a lower portion ofthe container C to some extent. When the energy applied to the upperportion of the container C is relatively larger than the energy appliedto the lower portion of the container C, the temperature of the upperportion of the container C can be maintained higher than the phasetransition temperature or a temperature of the maximum ice crystalformation zone. Further, the temperature of the liquid L in thesupercooled state can be adjusted by the energy applied to the lowerportion of the container C and the energy applied to the upper portionof the container C.

The liquid L has been described as an example with reference to FIGS. 3and 4. In the case of a received object containing a liquid, when theliquid in the received object is continuously supercooled, the receivedobject can be kept fresh for an extended period of time. The receivedobject can be maintained in a supercooled state at a temperature belowthe phase transition temperature via the above process. Here, thereceived object may include meat, vegetable, fruit and other food aswell as the liquid.

Furthermore, the energy adopted in the present invention may be thermalenergy, electric or magnetic energy, ultrasonic energy, light energy,and so on.

FIG. 5 is a schematic configuration view of the apparatus forsupercooling according to the present invention.

The apparatus for supercooling of FIG. 5 includes a case Sr mounted inthe storing unit S in which the cooling is performed and having areceiving space therein, a heat generation coil H1 mounted on the insideof the top surface of the case Sr and generating heat, a temperaturesensor C1 sensing a temperature of an upper portion of the receivingspace, a heat generation coil H2 mounted on the inside of the bottomsurface of the case Sr and generating heat, and a temperature sensor C2sensing a temperature of the lower portion of the receiving space or atemperature of a received object P. The apparatus for supercooling isinstalled in the storing unit S such that the cooling is performedtherein. The temperature sensors C1 and C2 sense the temperature and theheat generation coils H1 and H2 are turned on to supply heat from theupper and lower portions of the receiving space to the receiving space.The heat supply quantity is adjusted to control the temperature of theupper portion of the receiving space (or the air on the received objectP) to be higher than a temperature of the maximum ice crystal formationzone, more preferably, the phase transition temperature.

The positions of the heat generation coils H1 and H2 in FIG. 5 areappropriately determined to supply the heat (or energy) to the receivedobject P and the receiving space. The heat generation coils H1 and H2may be inserted into the side surfaces of the case Sr.

FIG. 6 is a graph showing the supercooled state of water in theapparatus for supercooling of FIG. 5. The graph of FIG. 6 is atemperature graph when the liquid L is water and the principle of FIGS.4 and 5 is applied thereto.

As illustrated in FIG. 6, a line I represents a curve of the coolingtemperature of the cooling space, a line II represents a curve of thetemperature of the gas Lg (air) on the surface of the water in thecontainer C or the case Sr (or the temperature of the upper portion ofthe container C or the case Sr), and a line III represents a curve ofthe temperature of the lower portion of the container C or the case Sr.A temperature of an outer surface of the container C or the case Sr issubstantially identical to the temperature of the water in the containerC or the case Sr.

As shown, in a case where the cooling temperature is maintained at about−19° C. to −20° C. (see the line I), when the temperature of the gas Lgon the surface of the water in the container C is maintained at about 4°C. to 6° C. which is higher than a temperature of the maximum icecrystal formation zone of the water, the temperature of the water in thecontainer C is maintained at about −11° C. which is lower than atemperature of the maximum ice crystal formation zone of the water, butthe water is stably maintained in a supercooled state which is a liquidstate for an extended period of time. Here, the heat generation coils H1and H2 supply heat.

Additionally, in FIG. 6, the energy is applied to the surface of thewater or the gas Lg on the surface of the water before the temperatureof the water reaches a temperature of the maximum ice crystal formationzone, more preferably, the phase transition temperature due to thecooling. Thus, the water stably enters and maintains the supercooledstate.

FIG. 7 is an exploded perspective view of a non-freezing storage unitaccording to an embodiment of the present invention, FIG. 8 is aperspective view of the non-freezing storage unit according to theembodiment of the present invention, and FIG. 9 is a sectional view ofthe non-freezing storage unit according to the embodiment of the presentinvention.

The non-freezing storage unit according to the embodiment of the presentinvention roughly includes an outer casing 100, a drawer 200 and a sidecasing 300. The drawer 200 can be inserted into and pulled out of theouter casing 100. As any separate electronic device is not attached tothe drawer 200, the drawer 200 can be completely separated and detachedfrom the outer casing 100. The outer casing 100 includes a thermalinsulation material 110 to insulate the non-freezing storage unit fromthe other region of a refrigerator in which the non-freezing storageunit is located. The drawer 200 and the side casing 300 also includethermal insulation materials 210 and 310, respectively. It is thuspossible to insulate the portions which are not sufficiently insulatedby the thermal insulation material 110 of the outer casing 100. Heaters140 are installed on the inside of the outer casing 100. A control unit(not shown) adjusts heating values of the heaters 140 to control atemperature in the non-freezing storage unit. The heaters 140 include anupper heater 142 and a lower heater 144, and the control unit (notshown) control the heating values of the upper heater 142 and the lowerheater 144, respectively. In addition, a sensor 132 for sensing atemperature in the unit which measures the temperature in thenon-freezing storage unit is installed on the upper side of the outercasing 100. In order to minimize the influence on the sensor 132 forsensing the temperature in the unit exerted by the heat of the heaters140, the heaters 140 may not be located adjacent to the sensor 132 forsensing the temperature in the unit, and a separate thermal insulationmember (not shown) may be further installed between the heaters 140 andthe sensor 132 for sensing the temperature in the unit. Moreover,sensors 134 and 136 sensing a temperature of food are provided on thelower side of the outer casing 100. The sensors 134 and 136 measure thetemperature of the food located in the drawer 200. Preferably, aplurality of sensors 134 and 136 are installed at given intervals toreflect the temperature of the food to the operation of the non-freezingstorage unit, when the food is widely distributed in the drawer 200. Inthis embodiment, although two sensors 134 and 136 are installed, threeor more sensors may be installed. As the sensors 134 and 136 are notinstalled in the drawer 200 brought into contact with the food but inthe outer casing 100, a cable for use in transferring power to thesensors 134 and 136 and receiving temperature sensing informationtherefrom can be removed from the drawer 200. There is an advantage inthat the drawer 200 can be completely pulled out of the outer casing100. If the drawer 200 is not completely pulled out of the outer casing100, it is inconvenient to put the food into the drawer 200 or take thefood out of the drawer 200 and very difficult to clean the drawer 200.The sensors 134 and 136 are attached to bottom surfaces of sensorinstallation portions 134 a and 136 a of a thin metal plate attached tothe bottom surface of the outer casing 100, and thus are not exposed tothe outside of the outer casing 100.

FIG. 10 is a view of a metal plate installed in the drawer of thenon-freezing storage unit according to the embodiment of the presentinvention, and FIG. 11 is a view showing a state where the metal plateis installed in the drawer of the non-freezing storage unit according tothe embodiment of the present invention. As described above, in thenon-freezing storage unit according to the embodiment of the presentinvention, since the drawer 200 can be completely pulled out of theouter casing 100 and separated therefrom, the sensors 134 and 136 arenot located in the drawer 200 but in the outer casing 200. There is adisadvantage in that the sensitivity of the sensors 134 and 136 sensingthe temperature of the food stored in the drawer 200 may be reduced. Tocompensate for this, a metal plate 232 receiving a temperature change ofthe food distributed in the drawer 200, and contact point portions 234and 236 transferring the temperature change of the metal plate 232 tothe sensors 134 and 136 are provided in a basket 230 of the drawer 200.The contact point portions 234 and 236 are downwardly protruded from thebottom surface of the basket 230. When the drawer 200 is completelyinserted into the outer casing 100, the sensor installation portions 134a and 136 a and the contact point portions 234 and 236 are brought intocontact without a gap, to thereby effectively transfer the temperatureof the food to the sensors 134 and 136.

FIG. 12 is a view showing a process in which the drawer of thenon-freezing storage unit of the present invention is inserted into theouter casing, and FIG. 13 is a view showing a state where the contactpoint portion and the sensor installation portion of the non-freezingstorage unit of the present invention are in contact with each other.The drawer 200 included in the non-freezing storage unit according tothe embodiment of the present invention includes the contact pointportions 234 and 236 downwardly protruded from the bottom surface of thebasket 230. When the contact point portions 234 and 236 are in contactwith the sensor installation portions 134 a and 136 a without a gap, thesensors 134 and 136 can sense the temperature of the food better.However, while the drawer 200 is moved in the outer casing 100, if thecontact point portions 234 and 236 continuously cause the friction incontact with the outer casing 100, problems occur such as the abrasionof the contact point portions 234 and 236 and the outer casing 100, thenoise caused by the friction, and an excessive force to push and pullthe drawer 200. Accordingly, it is preferable that the contact pointportions 234 and 236 should maintain a given interval from the bottomsurface of the outer casing 100 when the drawer 200 is moved in theouter casing 100, and should be brought into contact with the sensorinstallation portions 134 a and 136 a when the drawer 200 is completelyinserted into the outer casing 100. For this purpose, guide portions 120and 220 (see FIG. 12) guiding the movement position of the drawer 200 inthe outer casing 100 are provided in the corresponding positions of theouter casing 100 and the drawer 200, respectively.

The guide portions 120 and 220 include rails 122 and 222 and rollers 124and 224, respectively. When the drawer 200 is inserted into the outercasing 100, the rollers 124 and 224 of the outer casing 100 and thedrawer 200 are brought into contact with each other. Next, the rollers224 of the drawer 200 roll over the rails 122 of the outer casing 100and the rails 222 of the drawer 200 roll over the rollers 124 of theouter casing 100 at the same time such that the drawer 200 is insertedinto the outer casing 100. The rails 122 of the outer casing 100 areinclined to the lower portion so that the drawer 200 can be downwardlymoved at the back of the outer casing 100. In order to prevent therollers 224 of the drawer 200 from being separated from the rails 122 ofthe outer casing 100 due to the inclined portions, preferably, the rearportions of the rails 122 are blocked in a width to accommodate therollers 224. Additionally, to prevent the interference between thedrawer 200 and the rollers 124 of the outer casing 100 when the drawer200 is downwardly moved at the back of the outer casing 100, steppedportions are formed at the front of the rails 222 of the drawer 200 toaccommodate the rollers 124 of the outer casing 100. Therefore,referring to the drawings, while the drawer 200 is inserted into theouter casing 100 and moved therein, the contact point portions 234 and236 can be moved without any interference and friction, maintaining agiven interval from the bottom surface of the outer casing 100.Moreover, after the drawer 200 is completely inserted into the outercasing 100, the drawer 200 is downwardly moved by the guide portions 120and 220 and the contact point portions 234 and 236 are completely incontact with the sensor installation portions 134 a and 136 a.

FIG. 14 is an exploded perspective view of a front portion of the drawerincluded in the non-freezing storage unit according to the embodiment ofthe present invention. Referring to FIGS. 7 and 14, the front portion ofthe drawer 200 includes a front frame 240 defining the frame of thefront portion of the drawer 200 and connected to the basket 230, a cover250 covering the front of the front frame 240, a gasket 260 attached tothe back of the front frame 240 and sealing up between the outer casing100 and the drawer 200 when the drawer 200 is closed, a hook portion 272fixing the outer casing 100 and the drawer 200 to be closely attached toeach other when the drawer 200 is closed, an elastic member 274 applyingan elastic force to the hook portion 272, and a grip portion 276 whichcan release a locked state of the hook portion 272. In addition, thethermal insulation material 210 of the drawer 200 mentioned above isfilled in the front frame 240.

When taking the drawer 200 out of the outer casing 100 or inserting thedrawer 200 into the outer casing 100, a user can insert or take out thedrawer 200 by holding the cover 250 portion. For the user's convenience,a handle 252 is formed at the cover 250 portion. Any shape of handle 252may be used as far as it helps the user to easily take the drawer 200out of the casing 100. However, for the convenience of the use, thehandle 252 is formed in the shape of a groove on the lower side of thefront surface of the cover 250 so that the user can release the lockedstate of the hook portion 272 and pull the drawer 200 out at the sametime by gripping the grip portion 276. If the position of the gripportion 276 is changed, the position of the handle 252 may also bechanged so that the user can grip the grip portion 276 and pull thedrawer 200 out at the same time.

As set forth herein, the non-freezing storage unit should be certainlyinsulated from the other region of the refrigerator to stably maintainthe non-frozen state of the food. Here, a portion in which heat exchangewith the other region of the refrigerator or heat leakage probablyoccurs is a gap between the drawer 200 and the outer casing 100 locatedat the front. Accordingly, in order to ensure the thermal insulation ofthe drawer 200 and the outer casing 100, the gasket 260 is attached to arear portion of the front frame 240 brought into contact with a frontportion of the outer casing 100. The gasket 260 is made of an elasticmaterial such as natural rubber or synthetic rubber and transformedbetween the drawer 200 and the outer casing 100 by a force applied fromthe drawer 200 and the outer casing 100, thereby sealing up the gapbetween the drawer 200 and the outer casing 100.

As described above, when the drawer 200 is completely inserted into theouter casing 100, the drawer 200 is downwardly guided by the guideportions 120 and 220 (see FIG. 12). Since the guide portions 120 and 220(see FIG. 12) are inclined at the back, the drawer 200 receives a forcein the rearward and downward directions due to the self weight.Therefore, when the drawer 200 is completely inserted, the gasket 260 istransformed between the drawer 200 and the outer casing 100 due to theweight of the drawer 200 to seal up the gap. Moreover, the non-freezingstorage unit according to the embodiment of the present inventionincludes a hooked portion 172 and the hook portion 272 locking the outercasing 100 and the drawer 200 to enhance the sealing. To manipulate thehook portion 272, the grip portion 276 is located inside the handle 252of the cover 250 and rotatably coupled to the front frame 240. When theuser grips the grip portion 276 and holds the handle 252 with the gripportion 276, the grip portion 276 is rotated around coupling portions276 a located at both sides of the grip portion 276 and coupled to thecover 250 such that an upper part of the grip portion 276 pushes a lowerpart of the hook portion 272. The hook portion 272 is also rotatedaround coupling portions 272 a coupled to the cover 250 such that anupper part of the hook portion 272 is lifted from the hooked portion 172of the outer casing 100 and the coupling of the hook portion 272 and thehooked portion 172 is released. Thus, the user can pull the drawer 200out of the outer casing 100. Here, the elastic member 274 with both endsfixed by the hook portion 272 and the cover 250 is provided so that theupper part of the hook portion 272 can be firmly fixed to the hookedportion 172 of the outer casing 100 in a normal situation, pressing thesame. When the user grips the grip portion 276, the upper part of thehook portion 272 is lifted and the elastic member 274 is transformed,and when the user releases the grip portion 276, the upper part of thehook portion 272 is downwardly moved due to a restoring force of theelastic member 274. The outer casing 100 and the drawer 200 are fixed bythe hook portion 272 and the hooked portion 172. This ensures thesealing between the outer casing 100 and the drawer 200.

FIG. 15 is a view of a first example of an air layer structure includedin the non-freezing storage unit according to the embodiment of thepresent invention. As examined above, since the thermal insulationmaterial 210 is filled in the front frame 240 at the front surfaceportion of the drawer 200, the thickness of the thermal insulationmaterial 210 is smaller than that of the thermal insulation material 110inserted into the outer casing 100, which degrades the thermalinsulation effect. Accordingly, a protruding portion 280 is formed in a‘┐’ shape to prevent food from being put in proximity to the frontsurface of the drawer 200. While the protruding portion 280 preventsfood from being put in proximity to the front surface of the drawer 200,an air layer formed in the space where the food cannot be located due tothe protruding portion 280 can operate as a thermal insulation material.Therefore, the protruding portion 280 has a relatively highertemperature than the front surface of the drawer 200. Even if food isbrought into contact with the protruding portion 280, the food isprevented from being released from the supercooled state and frozen.

FIG. 16 is a view of a second example of the air layer structureincluded in the non-freezing storage unit according to the embodiment ofthe present invention. A plurality of pins 280′ protrude from the bottomsurface of the basket 230 of the drawer 200 to prevent food from beingput in proximity to the front portion of the drawer 200. In addition, aplurality of opening portions 290 are formed in the front portion of thebasket 230 so as to effectively transfer heat of the lower heater 144installed in the outer casing 100 to the front portion of the basket230. The flow between the drawer 200 and the outer casing 100 heated bythe lower heater 144 can be circulated by convection through the openingportions 290, and thus the temperature distribution in the non-freezingstorage unit can be more uniform. Preferably, a rib 292 enclosing theopening portion 290 is formed around the plurality of opening portions290 to prevent moisture of watery food or the like from being droppedinto the outer casing 100 through the opening portions 290. Meanwhile, abulkhead provided with a through hole to be able to produce a convectioncurrent, a plurality of pins protruding from the front surface of thedrawer 200 at a given height, or the like can replace the plurality ofpins 280′ protruding from the bottom surface of the basket 230, if theycan define an air layer to prevent food from being put in the frontportion of the basket 230 and the air layer can produce a convectioncurrent in the non-freezing storage unit. A sign preventing the userfrom putting food in the drawer 200 may be simply provided on the innersurface of the basket 230.

FIG. 17 is an exploded perspective view of the side casing provided inthe non-freezing storage unit according to the embodiment of the presentinvention.

The thermal insulation material 310, a control panel (not shown), acontrol panel mounting portion 320, an operation panel (not shown) andan operation panel mounting portion 330 are installed in the side casing300. The operation panel (not shown), which includes a button portion315 a, 315 b, 315 c and 315 d enabling the input of functions of thenon-freezing storage unit and a display portion 316 displaying theselected function, displays the function input through the buttonportion 315 a, 315 b, 315 c and 315 d on the display portion 316 andtransmits information on the inputted function to the control panel (notshown). Preferably, a window (hole) is provided in a correspondingposition of the side casing 300 to expose the button portion 315 a, 315b, 315 c and 315 d and the display portion 316 of the PCB operationsubstrate to the outside. The button portion 315 a, 315 b, 315 c and 315d and the display portion 316 are not located on the drawing 200 but onthe side casing 300 such that the drawing 200 is completely detachablefrom the outer casing 100. The button portion 315 a, 315 b, 315 c and315 d includes a button 315 a selecting a thin ice function, a button315 b selecting a freezing function, a button 315 c selecting asupercooling function, and a button 315 d turning on and off power ofthe non-freezing storage unit. The display portion 316 displays thepower-on/off state of the non-freezing storage unit and the functioncurrently performed in the non-freezing storage unit. When the userturns on power of the non-freezing storage unit through the button 315 dand selects the thin ice function through the button 315 a, the controlpanel (not shown) receives an input signal from the button 315 a anddisplays that the refrigerating function has been selected through thedisplay portion 316. In addition, the control panel (not shown) adjuststhe heating values of the heaters 140 installed in the outer casing 100(see FIG. 8) such that the temperature in the non-freezing storage unitranges from about −5° C. to −8° C. The control panel (not shown) adjuststhe heating values of the heaters 140 through the sensor 132 for sensingthe temperature in the unit and the sensors 134 and 136 such that thetemperature in the non-freezing storage unit exists in a desirabletemperature range. For example, when the meat is stored in thenon-freezing storage unit using the thin ice mode, it can be easily cutdue to thin ices. Moreover, when the user selects the freezing functionthrough the button 315 b, the control panel (not shown) turns off allthe heaters 140 and stores the food at the same temperature as that ofthe other region of the refrigerator without separate temperaturecontrol. Meanwhile, when the user selects the non-freezing functionthrough the button 315 c, the control panel (not shown) continuouslysenses the temperature in the non-freezing storage unit and thetemperature of the food through the sensors 132, 134 and 136 and adjuststhe heating values of the heaters 140 so that the temperature in thenon-freezing storage unit can be maintained at about −2° C. to −4° C.When the meat or the like is stored at a temperature below 0° C. withoutbeing frozen by the non-freezing function, it is possible to prevent thetaste from being reduced by the ice crystal formation in the meat andthe destruction of fibers of the meat.

In addition, while the meat is stored in the non-freezing storage unitby the non-freezing function, its non-frozen state may be broken due toa shock or partial temperature unbalance. Even if ice crystals areformed in some part, the freezing may be easily spread to the entiremeat. Once the freezing is started, the temperature is suddenly raisedto near 0° C. which is the phase transition temperature. Therefore, whena sudden temperature change is sensed by the sensors 134 and 136, it isdetermined that the stored food such as the meat, etc. has been frozen.The food in the non-freezing storage unit is thawed, and then storedagain in the non-frozen state. To thaw the food in the non-freezingstorage unit, preferably, the temperature is raised to near normaltemperature, at least 2° C. and maintained for a given time such thatthe food is sufficiently thawed and stored again in the non-frozenstate. Moreover, when the user selects the non-freezing function, thecontrol panel (not shown) may adjust the heating values of the heaters140 via a given algorithm using the sensor 132 for sensing thetemperature in the unit and the sensors 134 and 136 so that thetemperature in the unit can be maintained at −2° C. to −4° C. However,the control panel (not shown) may adjust the heating value of the upperheater 142 merely using the temperature sensed by the sensor 132 forsensing the temperature in the unit such that the temperature of theupper portion of the non-freezing storage unit is maintained at about−2° C., and may adjust the heating value of the lower heater 144 merelyusing the temperature sensed by the sensors 134 and 136 such that thetemperature of the lower portion of the non-freezing storage unit ismaintained at about −3° C. to −4° C.

FIG. 18 is a view showing an example in which the non-freezing storageunit according to the embodiment of the present invention is applied tothe conventional refrigerator. The refrigerator 1000 is divided into afreezing chamber 1100 and a refrigerating chamber 1200. The non-freezingstorage unit 2000 is installed in the freezing chamber 1100. When thenon-freezing storage unit 2000 is installed in the freezing chamber1100, the cool air cooling the freezing chamber 1100 cools the peripheryof the non-freezing storage unit 2000, and thus the meat in thenon-freezing storage unit 2000 is stored at a low temperature.Generally, the temperature in the freezing chamber 1100 ranges from −8°C. to −18° C., which is lower than a temperature for storing the meat ina non-frozen state. However, the control panel (not shown) adjusts theheating values of the heaters 140 (see FIG. 9) via a given algorithmusing the sensor 132 for sensing the temperature and the sensors 134 and136 so that the temperature in the non-freezing storage unit 2000 can bemaintained at −2° C. to −4° C., thereby keeping the meat in thenon-frozen state. The user may store the meat in a frozen state at thesame temperature as that of the freezing chamber 1100 without turning onthe heaters 140 (see FIG. 9).

FIG. 19 is a side-sectional view of the example in which thenon-freezing storage unit of the present invention is applied to theconventional refrigerator. The freezing chamber 1100 and therefrigerating chamber 1200 are arranged on the left and right sides inthe longitudinal direction in the refrigerator 1000, and thenon-freezing storage unit 2000 may be installed between shelves of thefreezing chamber 1100, or the topmost shelf or the bottommost shelf ofthe freezing chamber 1100. An evaporator 1300 is located on the rearsurface of the freezing chamber 1100 to exchange heat with the ambientair to produce the cool air. The cool air is introduced into thefreezing chamber 1100 to maintain the refrigerator 1000 at a lowtemperature.

The cool air heat-exchanged by the evaporator 1300 is introduced intothe freezing chamber 1100 through a cool air vent 2420 via a duct 1600.When the freezing chamber 1100 is cooled by the cool air, as far as theheaters 140 (see FIG. 9) are not operated, the temperature in thenon-freezing storage unit 2000 located in the freezing chamber 1100 ismaintained to be the same as that of the freezing chamber 1100. When theheaters 140 are operated by the control of the control panel (notshown), the temperature in the non-freezing storage unit 2000 ismaintained at −2° C. to −4° C. to store the meat in the non-frozenstate. The non-freezing storage unit 2000 may be fixed to the freezingchamber 1100 such that only the drawer can be opened and closed in theforward direction, or the non-freezing storage unit 2000 itself may beseparated from the freezing chamber 1100. When the non-freezing storageunit 2000 is manufactured to be separable from the freezing chamber1100, preferably, terminals transmitting and receiving electricity areformed in the freezing chamber 1100 and the non-freezing storage unit2000, respectively.

The present invention has been described in detail in connection withthe exemplary embodiments and the accompanying drawings. However, thescope of the present invention is not limited thereto but is defined bythe appended claims.

1. A non-freezing storage unit, comprising: an outer casing with an openfront surface; a drawer which can be pulled out through the open frontsurface of the outer casing; a sensor installed on the outer casingand/or the drawer; a heater installed in the outer casing; and an airlayer formed at the front of the drawer to intercept the cool air,wherein the non-freezing storage unit is located in a cooling space tostore food in a non-frozen state at a temperature below 0° C.
 2. Thenon-freezing storage unit of claim 1, wherein the air layer is separatedfrom a food storage space in the drawer by a protruding portionprotruding from the front surface of the drawer.
 3. The non-freezingstorage unit of claim 2, wherein the protruding portion is formed in theshape of ‘┐’ to be bent from the top to bottom.
 4. The non-freezingstorage unit of claim 1, wherein the air layer is separated from a foodstorage space in the drawer by a protruding portion protruding from thebottom surface of the drawer.
 5. The non-freezing storage unit of claim1, wherein the drawer is provided with a sign to prevent the food frombeing put in a space for defining the air layer.
 6. The non-freezingstorage unit of claim 1, wherein a thermal insulation material is filledin the inside of the outer casing.
 7. The non-freezing storage unit ofclaim 1, wherein, when the drawer is completely inserted into the outercasing, the bottom surface, the side surfaces and the rear surface ofthe drawer have a given interval from the outer casing.
 8. Thenon-freezing storage unit of claim 1, wherein the drawer comprises abulkhead separating the air layer from a food storage space in thedrawer.
 9. The non-freezing storage unit of claim 8, wherein thebulkhead comprises an opening portion for circulating the air in the airlayer and the storage room.
 10. The non-freezing storage unit of claim1, wherein the air layer is separated from a food storage space in thedrawer by a plurality of pins protruding from the bottom surface of thedrawer.
 11. The non-freezing storage unit of claim 1, wherein an openingportion is provided at the front of the bottom surface of the drawer,where the air layer has been formed, such that the air can be introducedfrom the lower portion of the drawer to the air layer.
 12. Thenon-freezing storage unit of claim 11, wherein a rib is formed aroundthe opening portion in the bottom surface of the drawer.